These days, if you asked people to name a famous Viking, most of them would probably find it quite a lot more difficult than naming a famous Roman. This is probably because so little was written down in Viking times - theirs was an oral culture, passed on by word of mouth - and very little was (literally) set in stone compared to Roman history.
The most memorable thing about the Vikings that people have heard of is often their nicknames: Ivar the Boneless, Erik Bloodaxe, or Sweyn Forkbeard - son of Harald Bluetooth (you'll find more about him if you click on the button). There is one character in Saving the Unicorn's Horn who actually existed: Sigtryggr, King of Jorvik. You'll find a little bit more about him, as well as a snippet about Erik the Red.